Definition 3 (\(\epsilon \) -covering) [1]} Let \((\mathcal {H}, d)\)  be a (pseudo)metric space, and \(\Theta \in \mathcal {H}\) . \(\lbrace h_1,\cdots , h_K\rbrace \)  is said to be an \(\epsilon \) -covering of \(\Theta \)  if \(\Theta \in \bigcup _{i=1}^K\mathcal {B}(h_i,\epsilon )\) , i.e., \(\forall \theta \in \Theta \) , \(\exists i ~s.t.~ d(\theta , h_i) \le \epsilon \) .

